If you can bend stuff so none of the welds are critical for strength, maybe, but typically plastic doesn't 'weld' like metal. The joins won't be as strong as the bulk material. Not saying plastic is bad, some of the moulded plastic guards are excellent, but they aren't made with welds.

I've certainly fixed things like indicator housings and handguards, but 'structural' strength is going to be a hard ask.

[QUOTE=VxZeroKnots;20705236]So after adventures in trying to get a skid plate to fit on my oddball bike I can't help but feel like I could make something better.QUOTE]

Grain shovel and a hammer.

Depending on what kind of plastic you are using, some weld better than others.I do what’s called (solvent welding) with MEK on ABS plastic with great success. ABS is what was mostly used on street/sport bikes fairings. I wouldn’t want to make a skid plate out of it thou.

I am also interested in buying a plastic welding iron. I gave it a try with a soldering iron and that works well enough that I'm prepared to buy the real gear. My polyethylene repair may not be as strong as original, but the original broke and the repair has held through multiple drops off-road.

The "trick" as far as I understand it is to prevent burning while also getting good penetration. Welding and brazing metal have helped me learn about plastic. I used plastic shaved off another piece -- my hypothesis being that it would be a similar material with similar melt point and a good chance of melding together.

Yes it's ugly. Yes a real plastic welding iron would probably make it look better. (It is not visible at all from the outside.)

The two things I'd look for are interchangeable tip shapes and adjustable temperature with a guide to setting the temperature for different types of plastic. I THINK that you can shave welding rod off the pieces you're using to make a project though that may not work for all types of plastic.

Plastic welding (when you know how) is a very stable joining method with strengths equal or greater than the base material.
Though the technique is somewhat different than gas welding or brazing the concept is there.
Countless tanks, fixtures, and structures are routinely fabricated from plastic and joined by hot gas welding. When done properly there is no concern for failure.

How well will a plastic skid plate function, I don't know. I think I'd call it a splash shield or stone guard and hope for the best. None the less it can be fabricated though it will most likely look bulky due to the material thickness required for strength.

A few points for the actual welding. Cleanliness of the base material and gas (air or N2) is utmost critical. Your not going to get away with an oil type air compressor with excessive moisture mixed in. A diaphragm type compressor with a method of moisture removal is good start.

If you can bend stuff so none of the welds are critical for strength, maybe, but typically plastic doesn't 'weld' like metal. The joins won't be as strong as the bulk material. Not saying plastic is bad, some of the moulded plastic guards are excellent, but they aren't made with welds.

I've certainly fixed things like indicator housings and handguards, but 'structural' strength is going to be a hard ask.

Pete

The stock skid plate which came on my bike appears to be HDPE and it is most certainly welded, the Hyde Racing skid plate also looks to have some welds on it at well. I think the key to strength is to make it all one piece and score the material at the bends so the weld only holds the material in place. I've never been one to be dissuaded by whether something was thought possible or not.

Quote:

Originally Posted by NJjeff

Plastic welding (when you know how) is a very stable joining method with strengths equal or greater than the base material.
Though the technique is somewhat different than gas welding or brazing the concept is there.
Countless tanks, fixtures, and structures are routinely fabricated from plastic and joined by hot gas welding. When done properly there is no concern for failure.

How well will a plastic skid plate function, I don't know. I think I'd call it a splash shield or stone guard and hope for the best. None the less it can be fabricated though it will most likely look bulky due to the material thickness required for strength.

A few points for the actual welding. Cleanliness of the base material and gas (air or N2) is utmost critical. Your not going to get away with an oil type air compressor with excessive moisture mixed in. A diaphragm type compressor with a method of moisture removal is good start.

This is what I want to hear! cheers! By they way, it is quite common these days in rock crawling is to use plastic skids, I expect some deformation under impact but am not worried about it, I just need to dissipate most of the energy. As to a source of gas, it looks like nitrogen is the way to go.

__________________

I say we take off and nuke the entire site from orbit. It's the only way to be sure

No bike does everything perfectly. In fact, no bike does anything until someone gets on it to ride.

If you are repairing a broken HPDE or other thermoplastic part, then welding is a good path IMO. However, if you want to make a skid plate from scratch, I would consider taking a piece of thin plywood as a base to make one out of fiberglass. The basic idea is to cover the plywood in epoxy and fiberglass cloth. Curves, etc. for the base plate can be made by adding molding material, such as modeling clay, and layering the fiberglass cloth on the mold. While it will take more time than welding, repairs can be made to restore the plate to original condition using the same technique.

However, learning to weld plastic would be more fun. Harbor freight sells an inexpensive hot air welder. Good luck!

Look up kydex, you can buy a large sheet then cut and shape it into the shape you need. The only tools you'll need are a heat gun and some good scissors. It comes in a variety of colors and thickness too.

The stock skid plate which came on my bike appears to be HDPE and it is most certainly welded, the Hyde Racing skid plate also looks to have some welds on it at well.

The Hyde racing skid plate on my DL is moulded, not a weld anwhere. I'm *very* happy with how tough it is, no problems with the right plastics being strong enough for this. The welding, not so confident.

I have plastic welded stuff, and the joins are weaker than the bulk material, it's a polymer - 'long chains of shit' holding it together, not metal - which is just irregular crystals jammed into one another. The problem is getting the 'long chains of shit' to bridge any gaps sucessfully, just melting it together is not guaranteed to work.

Not sayng you can't make a welded skid plate, just warning you that unlike metal welding where the joins can be as strong as or stronger than the bulk metal that's unlikely to be true with a plastic weld.

I'm happy for you to prove me wrong - but you asked if anyone had any experience - that was mine.

Fill one of these bait tanks with water and fish parts and you'll want a really strong tank even if it's welded plastic. Put that tank on a boat tossing on the ocean and the stress will be high although different from impact stress.

I have seen these guys at the local fair and they make rectangular tanks far larger than the 10 bushel tanks shown.